LASIK reshapes your cornea, the clear front surface of your eye, so that light focuses precisely on your retina instead of in front of it or behind it. An ultraviolet laser removes microscopic layers of corneal tissue to change the cornea’s curvature, and the entire procedure takes less than 30 minutes for both eyes. It’s the most commonly performed elective eye surgery, with 90 to 95% of patients ending up with 20/20 vision or better.
Why Reshaping the Cornea Fixes Your Vision
Your cornea does most of the work of bending light toward the back of your eye. When the cornea’s curve doesn’t match the length of your eyeball, light lands in the wrong spot. In nearsightedness, light focuses too early, in front of the retina. In farsightedness, it focuses too late, behind the retina. Astigmatism means the cornea is curved unevenly, scattering light in multiple directions.
Glasses and contacts compensate by bending light before it reaches the cornea. LASIK skips the middleman and reshapes the cornea itself, permanently changing how it bends light so images land directly on the retina.
The Two Lasers Involved
LASIK uses two different lasers, each with a distinct job. The first is a femtosecond laser, which fires ultra-short pulses that create tiny gas bubbles inside the cornea. These bubbles form along a flat plane, separating a thin hinged flap of tissue (roughly 150 microns thick, about the width of two human hairs). The surgeon lifts this flap to expose the thicker structural layer underneath, called the stroma.
The second laser, an excimer laser, does the actual vision correction. It emits pulses of ultraviolet light that vaporize corneal tissue with extreme precision, removing fractions of a micron at a time without generating heat. For nearsightedness, the laser flattens the center of the cornea. For farsightedness, it steepens the center by removing tissue from the edges. For astigmatism, it smooths out uneven curvature. Once reshaping is complete, the surgeon lays the flap back into position, where it adheres naturally without stitches.
What Happens During the Procedure
You’ll lie back under the laser while numbing drops take effect. A small device holds your eyelids open, and a suction ring centers over your pupil to keep the eye still. You may feel mild pressure but no pain. A glass lens flattens the cornea so the femtosecond laser can create a uniform flap.
Once the flap is lifted, you’ll be asked to stare at a fixed light while the excimer laser fires. The active laser time is typically under a minute per eye. You’ll hear a clicking sound and may notice a faint smell, which is vaporized tissue. The flap goes back down, the surgeon checks its position, and the process repeats on the other eye. Start to finish, most people are in the procedure room for 15 to 20 minutes.
Wavefront-Guided (Custom) LASIK
Standard LASIK corrects the same optical errors that glasses do: nearsightedness, farsightedness, and astigmatism. These are called lower-order aberrations. But your eye also has subtler irregularities that glasses can’t fix, things like glare sensitivity, reduced contrast, and halos around lights at night.
Wavefront-guided LASIK maps these irregularities by sending a special laser through the eye and measuring how the light bounces back, creating a detailed three-dimensional map unique to your eye. That map then guides the excimer laser to correct both the standard prescription and the finer optical imperfections. In FDA clinical trials, 94% of patients who had wavefront-guided treatment achieved 20/20 or better, and participants were four times more likely to say they were very satisfied with their night vision compared to how they saw with glasses or contacts.
Who Qualifies for LASIK
The excimer laser is FDA-approved to treat up to negative 14 diopters of nearsightedness, but most surgeons cap treatment around negative 9 diopters. Going higher requires removing more tissue, which increases risk. Your cornea also needs to be thick enough that after the flap is created and tissue is removed, at least 250 to 300 microns of structural cornea remains underneath. If your cornea is too thin or your prescription too strong, the math doesn’t work, and a surgeon will recommend alternatives like PRK or implantable lenses.
Beyond prescription and corneal thickness, several conditions rule out LASIK. The FDA lists autoimmune and collagen vascular diseases, immunodeficiency conditions, and pregnancy or nursing as contraindications. Uncontrolled diabetes is an absolute disqualifier, while well-controlled diabetes is a relative one, meaning some surgeons will proceed with caution. Severe dry eye that doesn’t respond to treatment, active eye infections, and unstable prescriptions (which is why patients must be at least 18, and ideally have a stable prescription for a year or more) also disqualify candidates.
Recovery and What to Expect After
Vision improvement is fast but not instant. Most people notice a dramatic difference within hours, though everything looks hazy and your eyes will feel dry and scratchy. By the next day, many patients can drive. You’ll likely notice halos around lights at night and vision that fluctuates throughout the day, sometimes sharper in the morning, sometimes in the evening. This is normal and typically continues for the first month or longer as the cornea heals and stabilizes.
Dry eye is the most common side effect. Immediately after surgery, roughly 95% of patients report some dryness. At one month, about 60% still notice it. For the vast majority, symptoms resolve between 6 and 12 months. A small percentage develop persistent dry eye that lasts beyond that window, which can be more difficult to treat. Your surgeon will have you using preservative-free artificial tears frequently in the weeks after surgery.
How Satisfied Patients Are Long-Term
LASIK has some of the highest satisfaction rates of any elective procedure. Clinical reviews consistently report satisfaction between 95 and 99%. In terms of visual outcomes, 99.5% of patients achieve at least 20/40 vision (the legal threshold for driving without glasses in most states), and 90 to 95% reach 20/20 or better. Some patients end up with 20/15 or even 20/10, which is sharper than what standard glasses typically provide.
Real-world patient reviews skew slightly lower than clinical trial data. On the review platform RealSelf, 78% of patients described LASIK as “worth it,” while about 13% said “not worth it” and 9% were unsure. The gap likely reflects the fact that people who experience complications are more motivated to leave reviews, but it’s a useful reminder that while most outcomes are excellent, a meaningful minority deals with lingering side effects like dryness, glare, or night vision changes that affect their overall satisfaction.